Various applications such as in the automotive field utilize structural foam to reinforce members. One form of application that has been suggested is to place the foam between side walls of a structural member. The placement may be facilitated by having the foam on a carrier which is inserted between the side walls where the foam is a heat expandable foam. The foam is initially bonded to the carrier and upon curing then becomes bonded to the structural member walls. In such approaches the foam is generally spread on the carrier in what would generally correspond to the final location where the foam would be in contact with the walls of the structural member so that upon curing there is assurance that the foam will contact the side walls and become intimately bonded to the side walls. With this technique, however, the foam may wipe against the side walls as it is being placed into the structural member. A further consideration with this technique is that the tacky foam may also contact the worker in, for example, an assembly line where the worker would be placing the foam and its carrier into the structural member.
An object of this invention is to provide a structural foam design which minimizes the tendency of the foam to wipe against the structural member and to be touched by the worker when the foam is inserted in place.
A further object of this invention is to provide such a structural foam which would be placed on a carrier wherein the foam is shaped and dimensioned in such a manner as to accomplish these objects.
In a preferred practice of this invention the carrier has a plurality of support surfaces onto which a layer of the structural foam would be placed. Each layer of the foam terminates inwardly of the outer edge of the support surface. Thus, when the carrier is inserted into the structural member with the outer edge of each support surface located at the walls of the structural member, the foam is spaced inwardly from the walls of the structural member thus minimizing any tendency for the foam to wipe against the walls while being inserted into the desired location. The carrier also includes sufficient portions free of the foam to function as a handle so that the worker may insert the carrier in place and minimize any tendency to touch the foam.
Preferably, the foam is expandable upon curing so that upon expansion the foam moves into contact with the side walls to be intimately bonded to the carrier and the side walls. In the preferred practice of this invention the foam is thermally expandable. This has the advantage in vehicle assembly lines of utilizing a conventional oven for the assembly line to cure the foam.
In a preferred practice of the invention the foam is extruded in block form and mounted on the support surface of the carrier. The carrier may generally be of I-beam shape having sloping walls which function as a pair of support surfaces. Where the foam is placed on each sloping wall the foam may be undercut to facilitate the foam moving downwardly and outwardly into contact with the structural member wall under the effects of gravity and the soft nature of the oven heated extrusion.